#include <bits/stdc++.h>
//#include <atcoder/modint>

using namespace std;
//using namespace atcoder;
using ll = long long;
//using mint = modint998244353;

ll isqrt(ll a){
    if (a == 0) return 0;
    ll l=1, r=3037000500, c;
    while(r-l>1){
        c = (l+r)/2;
        if (c*c <= a) l=c;
        else r=c;
    }

    return l;
}

int main(){
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);

    ll x;
    cin >> x;
    cout << isqrt(x) << endl;

    return 0;
}